In many telecommunications applications, microstrip antennas are employed. There are several types of microstrip antennas (also known as printed antennas), the most common of which is the microstrip patch antenna. A microstrip patch antenna is a narrowband, wide-beam antenna fabricated by etching an antenna element pattern in metal trace bonded to an insulating substrate. Because such antennas may be low profile, mechanically rugged and conformable, they are often employed on aircraft and spacecraft, or are incorporated into mobile radio communications devices.
Microstrip antennas are also relatively inexpensive to manufacture and design because of the simple 2-dimensional physical geometry. An advantage inherent to patch antennas is the ability to either transmit or receive (i.e. transceive) electromagnetic signals having polarization diversity. Patch antennas can easily be designed to have Vertical, Horizontal, Right Hand Circular (RHCP) or Left Hand Circular (LHCP) Polarizations with a single antenna feedpoint. This unique property allows patch antennas to be used in many types of communications links that may have varied requirements.
Another potential improvement for modern communications devices is the incorporation of waveguide architectures. Waveguides represent an effective mechanism for conveying signals with very little degradation or loss. Waveguides are commonly used in microwave communications, broadcasting, and radar installations. A waveguide consists of a rectangular or cylindrical metal tube or pipe. The electromagnetic field propagates lengthwise.
To function properly, a waveguide must have a certain minimum cross-sectional dimensions relative to the wavelength of the desired signal. If the waveguide is too narrow or the frequency is too low (i.e. the wavelength is too long), the electromagnetic fields cannot propagate. At any frequency above the cutoff (the lowest frequency at which the waveguide is large enough), the feed line will work well, although certain operating characteristics vary depending on the number of wavelengths in the cross section.
Mobility is a prime concern in the design of modern communications systems. Users are more likely than ever to require information in a variety of locales, thereby necessitating efficient mechanisms for ensuring the integrity of communicated data while minimizing the physical dimensions of individual communication system devices. Airborne TV antenna systems present a unique design challenge. Such antennas must be light weight, inexpensive, and capable of receiving dual circular-polarization (CP) radio frequency (RF) signals. Additionally, in order to be tail-mount compatible with medium size aircraft, the antennas must be able to fit in a package on the order of a 9″ swept volume.
Additionally, many current weather radars, including NEXRAD, transmit and receive radio waves with a single, horizontal polarization. However, the next generation of functionality in radar systems, such as polarimetric radar, may require a dual linear-polarization (LP) aperture.
As such it would be desirable to provide a low cost, light weight, high efficiency radiating antenna architecture capable of dual CP operation in an aircraft tail-mount compatible footprint or dual LP operation in weather radar.